std::pow implementation

[Robert Dewar]

> Martin is right that there is a lack of being able to express what one
> means. And which this lack you cannot be sure if the programmer with
> "inline" meant inline or maybe inline. You cannot even be sure if he meant
> do not inline if he omitted inline. It doesnt help that _you_ mean inline
> if you write it.

Note that in GNAT we have added pragma Inline_Always which says you absolutely
must inline, and it is an error if you cannot do so. pragma Inline means
that it is desirable to inline if it makes sense and is technically possible,
and not saying anything leaves the compiler free to inline if it thinks this
is a good idea (with most Ada code, this does not help much).